The specific hydroquinone as shown in formula (I) is known as a skin lightening compound. See WO9523780. ##STR2##
wherein Z is oxygen or sulfur.
The combination of the specific hydroquinone derivatives and penetration enhancers is disclosed in WO9523780.
WO9523780 describes that penetration enhancers are disclosed in U.S. Pat. No. 4,537,776, Cooper, issued Aug. 27, 1985; U.S. Pat. No. 4,552,872, Cooper et al., issued Nov. 12, 1985; U.S. Pat. No. 4,557,934, Cooper, issued Dec. 10, 1985; U.S. Pat. No. 4,130,667, Smith, issued Dec. 19, 1978; U.S. Pat. No. 3,989,816, Rhaadhyaksha, issued Nov. 2, 1976; U.S. Pat. No. 4,017,641, DiGiulio, issued Apr. 12, 1977; and U.S. Pat. No. 4,954,487, Cooper, Loomans & Wickett, issued Sep. 4, 1990, and additional penetration enhancers are disclosed in Cooper, E. R., "Effect of Decylmethylsulfoxide on Skin Penetration", Solution Behavior of Surfactants, Vol. 2 (Mittal and Fendler, eds.), Plenum Publishing Corp., 1982, pp. 1505-1516; Mahjour, M., B. Mauser, Z. Rashidbaigi & M. B. Fawzi, "Effect of Egg Yolk Lecithins and Commercial Soybean Lecithins on In Vitro Skin Permeation of Drugs", Journal of Controlled Release, Vol. 14 (1990), pp. 243-252; Wong, O., J. Huntington, R. Konishi, J. H. Rytting & T. Higuchi, "Unsaturated Cyclic Ureas as New Nontoxic Biodegradable Transdermal Penetration Enhancers I: Synthesis", Journal of Pharmaceutical Sciences, Vol. 77, No. 11 (November 1988), pp. 967-971; Williams, A. C. & B. W. Barry, "Terpenes and the Lipid-Protein-Partitioning Theory of Skin Penetration Enhancement", Pharmaceutical Research, Vol. 8, No. 1 (1991), pp. 17-24; and Wong, O., J. Huntington, T. Nishihata & J. H. Rytting, "New Alkyl N,N-Dialkyl-Substituted Amino Acetates as Transdermal Penetration Enhancers", Pharmaceutical Research, Vol. 6, No. 4 (1989), pp. 286-295.
Water-in-silicone composition are disclosed in GB patent publication No. 2079300A and U.S. Pat. No. 5,216,033A, but there are no description of the combination of the specific hydroquinone derivatives of formula(I) and the water-in-silicone composition, which works for enhancing penetration.
It is an object of the present invention to provide compositions for lightening mammalian skin which has a good penetration effect, so that the specific hydroquinone derivatives which are skin lightening actives can penetrate effectively and work effectively.